A mass spectrometer has a function capable of separating ionized molecules having masses at different charge ratios and may measure an ion current of each of them. In addition, the mass spectrometer may be divided into various types according to a method for separating ions.
As one of such mass spectrometers, there is a mass spectrometer for analyzing a mass using an ion trap. Such a mass spectrometer may use a cold electron ionization source as an ionization source for mass analysis, and inject an electron beam generated through the cold electron ionization source into an ion trap. At this point, the injected electron beam collides with a sample in the ion trap to generate ion molecules, and the mass spectrometer analyzes a mass using the generated ion molecules.
According to efficient generation of the electron beam, the number of the generated ion molecules and the precision of the mass analysis may be improved. However, due to positive and negative voltages periodically applied to a radio frequency (RF) electrode included in the ion trap, a phenomenon in which a part of electrons are ejected out from the ion trap occurs.
In this way, when the electrons are ejected out from the ion trap of the mass spectrometer, the precision of mass analysis is degraded. Accordingly, it is necessary to control the mass spectrometer to inject a large amount of electrons into the ion trap by the electron beam injection for precision improvement of mass analysis.